Sharon Tate's Sister Slams Auction of Murder House Front Door

Sharon Tate's sister is disgusted a guy is trying to make a buck off the door to the home where her sibling was butchered ... slamming the whole sale as immoral.

Debra Tate tells TMZ ... the current owner of the door, Christopher Moore, and the auction house through which he's peddling it, Julien's Auctions, oughta be ashamed of themselves for trying to profit off the murder of the late actress, who was 8 months pregnant at the time.

It goes without saying, there's a very dark history behind this former piece of the Tate house ... and Debra hopes whoever ends up buying the front door knows this, and realizes it isn't something to gawk at or marvel over. On the contrary, she says it's morbid.

She tells us the door should be destroyed, and the only reason it's even being sold and generating interest is due to the shock factor -- something Debra laments.

Debra says while she's horrified over the sale, she's actually not all that sure it's the real McCoy. Her reasoning lies in the details ... namely the design of the doorknob.

The door was well-documented in photos, and she insists if you look at the ribbing lining the handle in the OG ... it doesn't appear to match the handle on the door being hawked.

Moore and Julien's have assured us this door is authentic ... and have documented where it's been over the years. It seems folks believe it's legit ... the bids have soared past $22k.